Another M27

[MarkS]

Here is M27 taken under less than ideal conditions on Sunday night:
1) M27 was low in the sky
2) The sky was a bit dewy
3) Ambient temperature was 19C (a bit too high for the Canon EOS 300D) -  first day of Summer!!!

120min total exposure in 4 min subs with Astronomik CLS filter.  Final image is scaled by 2/3 and cropped.

This image will be used for comparison purposes once I have modded the 300D.

http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/m27_080608.jpg

[Rocket Pooch]

thats actually a lot better than some mono ccd'ers get, well done.

[Fay]

Excellant Mark. Can't believe you got that with your Canon. Obviously good things to come!

[Mike]

Tracking or stacking is off slightly as the stars are ellipses but it's a great image for a DSLR.

[JohnP]

Yep - have to agree Mark - that's very nice - John

[RobertM]

It certainly is exceptional for an uncooled camera but I'm sure it will be much better after the Ha mod.  I'm really looking forward to seeing the post mod result...

[JohnP]

I did a quick test last night with my Atik 16ic on m27 - I took a couple of frames each with CLS & then with Ha - amazing the difference between the two images. I'll post soon.

Cheers,  John

[MarkS]

Tracking or stacking is off slightly as the stars are ellipses but it's a great image for a DSLR.

It's the guiding that's at fault - it's not keeping the guidestar precisely central.  It drifts slightly from time to time.  I'm using PhdGuiding and the lead that runs from the serial port to the handset of the EQ6.

Do you think it would it perform better if I used a lead to ST4 port instead via the handset?

[Mike]

Are you not able to run a cable directly into the mount?

[Ian]

I'm reading it that you're using LX200 guiding commands over the serial link. I had a crack at that with my Vixen but never really had much success. I'm inclined to think that the processing time for the mount to react, and the general lack of precision in the LX200 protocol is getting in the way. I've now gone over to using the st4 port on my art285 connected to the guide port on the SS2K. Seems to react better with that...

[MarkS]

Yes I'm presently using the serial link to the handset of the EQ6.  I could try a lead direct to the mount instead (the ST4 port) - I just need to buy one. 

From what you are both saying, it sounds like that would give me more accurate guiding.

[Mike]

Probably easier and cheaper to make one Mark. I have a crimper you can borrow.

[Rocket Pooch]

Mark,

Go EQMOD you do not need a hand controller and it brilliant, I can guide sub pixel for ever and hop stars etc with it, if you want to have a look pop around.

Chris

Also you do not need a ST4 cable.

And you can control the telescope from 20 meters using a rumblepad.

[RobertM]

Another excellent image Mark, you're really on a roll at the moment.  You do need to sort out that guiding, ideally you only want corrections in RA so that means perfect polar alignment.  I'm not sure about EQMOD but some mounts need an ST4 type control connection so the guider can control the mount motors directly.  Reactions are quicker and proportional to the movement needed whereas if you have guide software controling the mount then the correction pulses are for a fixed time/distance movement.  This can lead to over/under correction especially if the mount only accepts guide commands on a periodic basis.  Don't forget that a guide correction is only needed if the guide star has moved and so by definition there will always be some trailing however small and insignificant (which is what you are after).

Robert

[MarkS]

I now have an image taken last night with my DIY modded EOS 300D.  Below are the "before" image (on the left) and "after" image (on the right):



Both images are 24 x 5min and I've tried to scale them so the nebulous blue is looks approximately the same in both.

Some comments:
1) In the "after" image I had to reduce the red component by a factor of 2.5 to prevent it swamping the image.
2) The blue looks less noisy in the "after" image.  This is because last night the temperature was cooler (16C vs 19C) and also the wind helped cool the camera.
3) The stars in the "after" image are more elliptical because of the gusting wind last night.
4) All stars appear brighter in the second image - some dramatically so.  It is very noticeable against the nebulous blue.

[mickw]

Nice work Mark, certainly a worthwhile mod.

I wasn't expecting the difference to be quite so dramatic

[Fay]

Mark, that is really good. A very good improvement.

I tried to do NGC888 & the Veil. I have tried a couple of times, but have assumed, as the image is quite light & all over red, that the sky is too bright at the moment. Although a lot of red is expected in that area.

I was testing all evening to see how I could get a reasonable frame regarding lightness. Around 12.30, I tried out a 600 sec of NGC888. It was the darkest it had been, but very red all over.

Do you think I should alter the red component, even though I was in a very red area? Also, do you use Photoshop for processing? I am not sure how to use the levels & curves with  RGB all in the same frame.


Fay

[Fay]

Mark, I will sort myself out & put the image on the forum. I did various times during the evening, but feel for Ha I need the longer exposures.

[MarkS]

Fay,

What you are describing is exactly what I found last night - the background was quite red (even with a CLS filter) and all the stars were very red.  This is exactly what you expect to find with a modded camera.  This is why I scaled back the red channel using RGB balancing.  I don't use Photoshop (except on rare ocasions) but I'm sure there must be an equivalent way to re-adjust the balance of the  RGB channels.

Mark

[Fay]

I used a CLS filter as well. Earlier on I did some exposures with 0.8 FR, but decided to take it off.They were so light.

[Rocket Pooch]

Oh, I like the after.

Mark/Fay I HAVE A 2" FILTER I HAVE NOT USED YET (BAARDER UHC-S), YOU CAN BORROW IT... 


But you house is subject to repossession if you do not return the filter in original condition.


HINT!!!!!!!!!!!!!!!!!!!!!!!!!!

[MarkS]

The "after" image with slightly more sympathetic processing.  The bluish star right at the centre is more obvious now.

[Fay]

Mark, fantastic perfect image, camera mod obviously paid off.
Can't believe the time you were up, this morning!

[MarkS]

Thanks Fay, I'm pretty pleased with the result.

I'm looking forward to some images from your modded 350D ...

[Mike]

Nice one Mark.

[JohnP]

Mark - that does look good - once you get your guiding sorted it'll be excellent.... John

[Rick]

Today's APOD image makes an interesting comparison:

http://apod.nasa.gov/apod/ap080626.html

[MarkS]

That's a beautiful APOD image.  But he has an unfair advantage by using a robotic telecope in Hawaii !

[Ian]

does that mean you don't consider yours to be robotic?

Anyway, who needs Hawaiian skies? Take advantage of the sky glow to get shorter exposures. More time drinking beer

[Rocket Pooch]

I'm in wales next week, so you should have clear skies Tues/Wed

[MarkS]

Last night, although the conditions were windy and the moon was 2 days after full, I managed to get 2 hours of data from the modified Canon 350D.

So below, we have in order:
1)  Unmodified Canon 300D   -  Ambient temp 19C and still.
2)     Modified Canon 300D   -  Ambient temp 16C and windy
3)     Modified Canon 350D   -  Ambient temp 16C and windy

All are taken with the Celestron C11 with F6.3 focal reducer on EQ6 mount with guiding.
All are 24 x 5min
All are scaled by 2/3 and then cropped.
The Canon 350D image is slightly larger because it is 8 Mpixels instead of 6 Mpixels. 

[Edit] All were taken from Sidcup using an Astronomik CLS filter.

The 350D image does show a bit more detail in the very faint areas but the improvement is marginal.  The 350D colours are a bit more bland but I could have done a bit more processing to match them better.

[JohnP]

Excellent comparison Mark - I actualy prefer the modified 350D image - I like the colour (slight more greeny (less blue))....

It'll be interesting to see what you get with this from a dark site.

John

[RobertM]

I have to agree with you John, the colours are more what I would expect.  The 350d image has more stars - is it really more sensitive or is it the post processing that's made them different ?

[MarkS]

The difference is not in the 350D's sensitivity but in the massively reduced dark current and read noise.  This allowed me to increase the gain when processing the 350D to bring out more detail.

I'll do a further test where I perform identical processing on each - that could be quite interesting ...

[MarkS]

Here we are - identical processing on each - the subs are just stacked with no range compression applied. 
No RGB balancing has been done, so the colour balance is just how it came off the CCD.
Each image is 24 x 5min at ISO 800 using a CLS filter.
They are 2x2 binned in software and cropped.

Left to right:
Canon 300D unmodified
Canon 300D modified
Canon 350D modified

[RobertM]

That's interesting, the 300d does very well but I think the colour balance in the 350d is much better for the OIII emission line.  Ha doesn't really seem much different other than for the image scale.

[Rocket Pooch]

I like the 300D image, best because the colours look right, only my opinion though.

Anyway, are you going to try the AMP off mod or cooling?

Chris


P.S. Does anyone want to use my 6 inch F5 at DSC, I have a specific image I'm after so I might not use it until later this year.